1. Field of the Invention
The present invention relates to a method for reducing perceivable noise in a vehicle and more specifically, to a method for reducing the perceivable audible noise in the interior of a vehicle from rotating components such as fans and blowers.
2. Discussion
Consumers have long associated quiet operation of components in vehicles with quality and luxury. This association is particularly true for automotive vehicles and manufactures of automobiles and related transportation equipment continually strive to reduce noise levels in the interior of vehicles. The primary causes of noise in a vehicle have traditionally been engine noise, air or wind noise, and road noise. While these traditional noises are still the primary cause of noise in the interior of a vehicle, manufacturers have successfully reduced these noises to a level where other noises, traditionally not noticed by consumers, are now part of the list of primary noises heard by the occupants of a vehicle. More specifically, as manufacturers have improved tread design of tires to reduce tire noise, vehicle aerodynamics to reduce air or wind noise, and insulation and other noise reducing technology such as improved seals to reduce audible noise within the interior of the vehicle. With such noise reductions, noises from various rotating components on the vehicle are now audible to consumers and a new source of noise complaint.
One rotational component that traditionally produces audible noise within the vehicle interior, but has become particularly acute and noticed by the occupants of a vehicle due to the overall general noise reductions in the interior of vehicles is the heating and cooling blower fan. Traditionally, consumers directly controlled the speed of the blower or fan and thereby also controlled the amount of noise the fan or blower would produce. Most consumers set the speed of the fan as a balance between the speed which was directly proportional to the amount of cooling or heating provided to the interior of the vehicle against the amount of noise the fan or blower made at the set speed. If the particular speed of a fan was too noisy, the speed would be easily manually adjusted by the consumer. Recently, as more and more vehicles come standard with automatic climate control systems, consumers have lost the ability or have found it difficult to adjust the speed of a fan directly as it is instead automatically controlled by an automatic climate control system. In automatic climate control systems, the system will automatically adjust the speed of the fan to control the amount of hot, cold or fresh air being provided to the interior of the vehicle along with other parameters to maintain or reach a specified temperature level within the interior of the vehicle. Due to this loss of control by occupants of the vehicle, as well as the prevalent change of fan speed by the automatic climate control system to maintain or adjust the interior temperature of the vehicle, and the recent reduction in audible noise in the interior of the vehicle, consumers are increasingly noticing of the noise produced by the heating and fan or blower.
In an attempt to address complaints related to the noise level of the fan or blower, manufacturers have redesigned the shape of the fan blades, vents and other components to reduce audible noise. To maintain efficient movement of air by the vehicle fan, many of these redesigns to the fan shapes are limited. Therefore, it is difficult to obtain any further noise reductions from redesigning the shape of the fan blades or vents and it is desirable to find other ways to reduce the audible noise produced by a rotating components in vehicles, in particular for automatic controlled climate systems where a fan maintains the vehicle temperature without consideration to the noise caused by the fan.
As noise levels in the interior of vehicles have been reduced, some consumers have noticed noise from rotational components other than the heating and cooling fan. These rotational components may be located both within the vehicle compartment and outside of the vehicle compartment. Examples of such other rotating components in the vehicle compartment include electronic cooling fans and other cooling fans, such as, cooling fans include cooling fans for radios, navigational systems, video devices, video displays, CD players and changers, voltage converters and instrument panels. Of course, the previous list is not an exhaustive list of the many rotating components such as fans found in a vehicle. Other cooling fans may include supplemental heating and cooling fans, cooling fans for vehicle seats, and in some vehicles fans for chilling or warming compartments to keep items like beverages either hot or cold within the compartment. An example of a rotating component outside the vehicle compartment is the cooling fan for the radiator and engine. Traditionally these rotating components or fans were not audible to the occupants of the vehicle' due to the existing audible noise in the interior of the vehicle however, with recent noise reduction in the vehicles, these rotating components particularly at stopped states or lower vehicle speeds are now noticeable to the occupants of the vehicle. In particular, these rotating components are noticeable to the occupant of the vehicle as they cycle between on and off states. Therefore, it is desirable to provide a system and control method for reducing the audible noise of certain rotational components within the interior of a vehicle.